Jeffrey C. Miller

Infestation of Wild and Ornamental Noncrop Fruits by Drosophila suzukii (Diptera: Drosophilidae)

ABSTRACT Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a pest of small fruits and cherries, and has also been noted to infest a variety of wild, ornamental, and uncultivated hosts. Identifying alternative hosts is critical for pest management. Research objectives were to: 1) survey fruits in the field for natural infestation of D. suzukii, 2) determine the susceptibility of fruits in laboratory no-choice studies, and 3) evaluate short-range preference between simultaneously ripe alternative hosts and cultivated fruits in laboratory choice studies. Field surveys identified new hosts or confirmed previously reported hosts including: Berberis aquifolium Pursh, Oregon grape; Cornus spp., dogwood; Cotoneaster lacteus W.W. Smith, milkflower cotoneaster; Elaeagnus umbellata Thunberg, Autumn olive; Frangula purshiana (de Candolle) A. Gray, cascara buckthorn; Lindera benzoin (L.) Blume, spicebush; Lonicera caerulea L., blue honeysuckle; Morus sp., mulberry; Phytolacca americana L., pokeweed; Prunus avium (L.) L., wild cherry; Prunus laurocerasus L., cherry laurel; Prunus lusitanica L., Portuguese laurel; Rubus armeniacus Focke, Himalaya blackberry; Rubus spectabilis Pursh, salmonberry; Sambucus nigra L., black elderberry; Sarcococca confusa Sealy, sweet box; Solanum dulcamara L., bittersweet nightshade; and Symphoricarpos albus (L.) S.F. Blake, snowberry. High fruit infestations were observed in S. confusa during April—May and Lonicera spp. in June before most commercial fruits ripen. From both field and laboratory studies, there was no evidence of susceptibility during the estimated ripe period Crataegus L. ‘Autumn Glory,’ hawthorn; Ilex crenata Thunberg, Japanese holly; Nandina domestica Thunberg, sacred bamboo; Rhaphiolepis umbellata (Thunberg) Makino, yeddo hawthorne; Rosa acicularis Lindley, prickly rose; Skimmia japonica Thunberg, Japanese skimmia; and Viburnum davidii Franchet, Davids viburnum. Lastly, laboratory choice tests identified that several fall-ripening alternative hosts were more susceptible than ‘Pinot noir’ or ‘Pinot gris’ wine grapes. By understanding host use, growers can identify high-risk areas where coordinated action may reduce infestation of D. suzukii in crops.

Insect natural history, multi-species interactions and biodiversity in ecosystems

The composition and dynamics of ecosystems are influenced by insects serving as providers, eliminators and facilitators across multiple trophic levels. The role of insects in ecosystems may be documented by manipulative field studies involving exclusion techniques applied to species that are decomposers, herbivores or predators. The presence or absence of insects is important to the distribution, abundance and diversity of plants and vertebrates, which typically are the premier species in conservation efforts. Thus, policy-making in environmental management programmes should consider the role of insects in ecosystems when establishing objectives and procedures for species conservation and biodiversity.

Ground dwelling beetles and forest vegetation change over a 17-year-period, in western Oregon, USA

Regrowth and old-growth Douglas-fir stands were sampled for ground dwelling beetles using pitfall traps in 1982, 1983 and 1999. Species richness and abundance was compared within and among years, plots, and age of forest using multivariate techniques. Representatives of 49 families and 224 taxa were collected for a total of 11,191 specimens. The abundance and species richness of ground dwelling beetles suggested four notable relationships. First, different ages of forest had significantly different beetle communities. For instance, the herb stage regrowth stands supported a number of seral specialists including: Microlestes nigrinus Mannerheim and Trachypachus holmbergi Mannerheim. Second, specifically defined plant communities were associated with unique beetle communities. Ordination analysis showed that the grouping of stands, based on beetle communities, was correlated with differences in vegetative characteristics. Third, over a 17-year-period, beetle communities in old-growth stands remained relatively stable while beetle communities in regrowth stands exhibited a high degree of change. Ordination analysis grouped old-growth stands regardless of year sampled, while young seral stands changed significantly in regards to their ordination position depending on sampling year. Fourth, beetle communities in regrowth stands changed in a manner that paralleled the predictable transformation of young plant communities into mature forest stands. Ordination analyses found that beetle communities in the herb stage regrowth stands of 1982 had changed significantly and exhibited characteristics of beetle communities in tree stage regrowth stands.

Effects of nitrogen and Douglas-fir allelochemicals on development of the gypsy moth,Lymantria dispar

Two experiments were conducted to examine the influence of foliar nitrogen, terpenes, and phenolics of Douglas-fir on the development of gypsy moth larvae. In the first experiment, foliar concentrations of nitrogen and allelochemicals were manipulated by fertilizing 3-year-old potted seedlings with 0 or 200 ppm nitrogen. Concentrations of foliar nitrogen (0.33–2.38%) were negatively correlated with the phenolics (15.8–24.4 mg/g). Sixth-instar larvae previously reared on current-year Douglas-fir needles were allowed to feed on these seedlings. Pupal weights (312.8–995.6 mg) were positively correlated with levels of foliar nitrogen, negatively correlated with amounts of foliar phenolics, and uncorrelated with terpene concentrations. In the second experiment, terpene and phenolic extracts from Douglas-fir foliage were incorporated at natural levels into artificial diets with high and low levels of protein nitrogen. Neonate larvae grew faster and were larger on the high nitrogen control diet (4.1–4.5%), however, fourth instars performed better on the control diet with low nitrogen levels (2.5–2.7%). Foliar terpenes incorporated into diet had little effect on neonate fitness, but may induce subtle physiological changes in later instar larvae. Phenolics, alone or in combination with terpenes, excessively suppressed growth and survival, with no individuals living through the fourth instar, regardless of the nitrogen level. Incorporating foliar phenolic extracts into artificial diet caused unnatural levels of toxicity and failed to clarify the effects of Douglas-fir phenolics on gypsy moth fitness. Foliar nitrogen is a key factor influencing gypsy moth development on Douglas fir, but may be mitigated to some degree by phenolics.

Niche Relationships Among Parasitic Insects Occurring in a Temporary Habitat

Patterns in the parasitism of a lepidopteran host, Spodoptera praefica, were assessed through an analysis of niche relationships among the parasitic species. No parasitized hosts were recovered from nondisrupted habitats. However, three species, Chelonus insularis, Apanteles mar- giniventris, and Hyposoter exiguae, commonly parasitized S. praefica in a disrupted habitat (mowed alfalfa field). Overall, H. exiguae was numerically dominant as well as the most rapid exploiter of hosts following habitat disruption. Species diversity within the parasitoid guild significantly increased with time following each habitat disruption. Significant trends were also observed in species evenness. The niche breadth of C. insularis and H. exiguae varied with time of year and time following habitat disruption while the niche breadth of A. marginiventris remained relatively constant. Niche overlap was generally high between the two larval parasitoids, A. marginiventris and H. exiguae, and low between these species and C. insularis, an egg-larval parasitoid. The values determined for species diversity, niche breadth, and niche overlap suggest that a low degree of temporal stability rather than interspecific competition strongly influenced species composition within the parasitoid guild of S. praefica.

Effects of temperature on larval eclosion of the winter moth, Operophtera brumata

The developmental threshold and heat‐unit requirements for larval eclosion of the winter moth, Operophtera brumata (L.) [Lepidoptera: Geometridae], were determined from experiments involving eggs exposed to various chilling and warming treatments. The developmental threshold was determined to be 4 °C. Eggs which were chilled below the developmental threshold required fewer heat‐units for larval eclosion than did eggs not given a chill treatment. Eggs cultured at 14 °C required 470 (± 47) degree‐days for 50% larval eclosion. However, eggs chilled for 2 weeks at 1 °C and subsequently placed at 14 °C required 382 (± 33) degree‐days while eggs chilled for 12 weeks at 1 °C and subsequently placed at 14 °C required 156 (± 12) degree‐days. The results are discussed in relation to chilling intensity, diapause, and physiological‐time models.

First Fossil Record of Endoparasitism of Adult Ants (Formicidae: Hymenoptera) by Braconidae (Hymenoptera)

Abstract A parasitoid wasp larva is described emerging from an adult ant (Lasius sp.) in Eocene Baltic amber. On the basis of the cephalic structures of the parasitoid, it can be assigned to the subfamily Neoneurinae of the family Braconidae. This is the only extant subfamily of Hymenoptera whose females oviposit in adult worker ants. This discovery, which is the first fossil demonstrating insect parasitism of ants, shows that ant parasitism by Braconidae was well established some 40 million years ago. The parasitoid could belong to the extinct neoneurine, Elasmosomites primordialis Brues, which was described earlier from Baltic amber.

Life history of insect parasitoids involved in successful multiparasitism

SummaryThe occurrence of multiple parasitoid emergence from individual hosts was observed on numerous occasions. Characteristically such a phenomenon is extremely rare. In the observed instances of successful multiple parasitism of Autographa californica the parasitoid life history attributes of partial host consumption, gregariousness and timing of host parasitism are suggested as traits which contributed to certain species being able to coexist within individual hosts.

Determinants of moth diversity and community in a temperate mountain landscape: vegetation, topography, and seasonality

Macromoth diversity, abundance, and community structure in the topographically complex HJ Andrews Experimental Forest and LTER site was studied on the west slope of the Cascade Range, Oregon. Data on 493 macromoth species (62,221 individuals) was sampled eight times/year at 20 locations from 2004 to 2008 and examined using multivariate statistics and generalized additive models to determine the importance of topography and vegetation on moth community assembly and diversity. Significant differences exist between moth communities at lower and higher elevations. High-elevation moth communities are far more variable inter-annually, whether associated with high-elevation forests, meadows, or clearcuts. Low-elevation young and old gymnosperm forests and riparian forests are more stable and predictable communities having less inter-annual variability. High-elevation communities show more intra-annual variability than low-elevation communities. Low-elevation moth communities are more abundant than high-elevation...

Distribution and Functional Roles of Rare and Uncommon Moths (Lepidoptera: Noctuidae: Plusiinae) Across a Coniferous Forest Landscape

Abstract The temporal and spatial distribution and abundance of 15 rare to uncommon species of plusiine moths were compared across a watershed landscape dominated by a coniferous forest located on the western slope of the Cascade Mountains in Oregon. The 5-yr study assessed the species in the context of functional roles related to caterpillar host plants categorized into three guilds: conifer, hardwood tree and shrub, and herbaceous-feeding species. Also, the landscape was considered in the context of five geographic zones based on elevation and habitat type. Species richness and abundance were highest within the herb-feeding guild, seven (47%) species and 74 (47%) individuals. The conifer-feeding guild consisted of four species (27%) and 64 (40%) individuals, whereas the hardwood tree and shrub guild consisted of four species (27%) and 21 (13%) individuals. In combination, zones II, III, and IV, high elevation sites with extensive subalpine meadow habitat, exhibited a species richness of 14 (93%) and 119 (75%) individuals. Six species occurred in only one of the five zones, and three of these species occurred in zone II, a mid to high elevation zone with a total of nine plusiine species. Only 3 of the 15 species occurred in all five zones; each of these species represented one of the three feeding guilds and exhibited their highest abundance in zone III, a high elevation site with extensive subalpine meadow habitat. The presence of subalpine meadows contributed to increasing landscape heterogeneity across the watershed and was the primary factor contributing to the overall species richness among the Plusiinae within the H.J. Andrews Experimental Forest by providing a suitable environment for species in the herb-feeding guild. We suggest that, in a context that may be generalized to other environments and other taxa, the additive effects of rare and uncommon species with special or restricted habitat requirements provide an important contribution to the biodiversity within a local landscape. Furthermore, environments with a relatively high degree of temporal variability, such as meadows and other early successional plant communities, can be a major factor in contributing to the biodiversity within a local landscape.